The present invention relates to a brake device for a drive machine of an elevator, comprising brake arms which are supported in swiveling manner on a bearing pedestal and have brake shoes which act on a brake drum, the brake arms being guided at their free ends by means of a fixed guide element and pressed against by compression springs acting in the direction of the guide element, magnets being provided which act in opposition to the compression springs to release the brake shoes.
European patent specification EP 0 603 644 shows a known brake device having a brake drum that is fastened to a traction sheave and against which brake shoes held in swiveling manner on brake arms rest. The brake arms are arranged at one end to pivot on axles. At the other end, a tie rod is provided which passes through the brake arms, and a compression spring is arranged at each end of the tie rod. The compression spring presses at one end against an end stop of the tie rod, and at the other end against the brake arm. The end stop can be moved by means of an adjusting screw, causing the brake shoe to be pressed to a greater or lesser degree against the brake drum. An actuating bolt passes through the free end of each brake arm. Both actuating bolts are acted on by a force originating in each case from a magnet, and acting in opposition to the spring force of the compression springs, so that the brake shoes are raised from the brake drum.
A disadvantage of this known brake device is that with brake devices for larger drive machines, the transmission of large braking forces onto the brake drum is not possible without additional measures, for reasons of material deformation. Furthermore, monitoring the position of the brake shoes requires a substantial capital outlay.
The present invention concerns a brake device that provides a solution to avoiding the disadvantages of the known brake devices and creates a brake device with which larger drive units can be reliably braked.
The advantages achieved by the invention are that with a simple construction of the brake device, and of the bearing pedestal supporting the brake device, a rigid brake device can be made with which, especially, greater braking forces can be transmitted onto the brake drum without problem. Furthermore, the stability of form, and the function, of the brake release system can be improved at the same time as the material outlay and weight are reduced. With the brake device according to the present invention, the accuracy of the instant at which the brake is released can be improved, which again has a positive effect on the ride comfort of the elevator car. Arranging the sensors to monitor the brake arms, and wiring the brake magnets, is possible without great capital outlay.